Scientists at Stanford University have built ant-sized radios that could one day help track patients' temperatures, turn on coffee makers in the morning and prevent forgery.

A Stanford engineering team has built a radio, equipped with sensors, computational units and antennas one-tenth the size of Wi-Fi antennas, that is able to gain all the power it needs from the same electromagnetic waves that carry signals to its receiving antenna. No batteries are required.

These radios, which are designed to compute, execute and relay commands, could be the key to linking gadgets together in the increasingly popular idea of the Internet of Things.

Today's radios generally are the size of a quarter, according to Amin Arbabian, assistant professor of electrical engineering at Stanford and a researcher on the radio project. These new radios are much smaller. They're 3.7 x 1.2 millimeters.

That's the size of an ant.

Radios that small could be added to everything from $100 bills to medical gauze, Band-Aids and home appliances. At just pennies per radio, that means a myriad of products could easily and cheaply become part of a linked network.

"This could be very important," Arbabian told Computerworld. "When you think about the Internet of Things, you're talking about needing a thousand radios per person. That counts all the radios and devices you'd need around you in your home and office environments. With 300 million people in the U.S., we'd have 300 billion radios."

A Bluetooth-type radio works fine for smartphones but is too big and expensive to connect most of the objects in users' lives.

"We needed the cost and size to go down, and you need scale," said Arbabian, who began working on the project in 2011. "Do you want to put something the size of a Bluetooth radio on a Band-Aid? It's too big. It costs a lot. The technology we have today for radios doesn't meet any of these requirements."

He explained that a tiny radio with a temperature sensor could be put on a bandage or piece of adhesive that's applied to every patient that enters a hospital. The radio and its sensor would enable the medical staff to continuously track every patient's temperature, a key health indicator, effortlessly and cheaply.

Sensors also could be used to measure air quality, to track medications from the manufacturer to the end user and to even keep track of tools and supplies in an operating room. For instance, Arbabian noted that a radio, encased in bio-safe material, could be attached to gauze or medical tools. With them, everything in an operating room could be tracked to ensure that nothing is left inside the patient at the end of surgery.

The radios also could be attached to every day products inside the home, including appliances, doors and windows.

One radio sensor may detect that a door has opened and someone has entered the room. That radio could connect with others that might switch on a coffee maker or turn on the air conditioning.

Radios are simple devices. Each one has a tag ID number built into it, Arbabian explained. When contacted, the radio will respond with its identifying number and its location. Along with sensors and a receiving, as well as a transmitting, antenna, the radio also carries a basic computational unit. Much less sophisticated and complex than, say, an Intel Pentium processor, this chip can handle only about five or six instruction sets but consumes very little power.

The Stanford team designed each piece of the radio, down to the computer chip.

The radio range is limited to about two to three meters. Arbabian said he could double the range but would need to double the size of the radio to do it.

"There's a tradeoff there," he added. "If you want five meters, you might make it twice the size. The bigger it is the longer the range. The smaller it is the shorter the range."

Because the research team has a framework for the radio's design, Arbabian said it's fairly simple for them to take it from one dimension to another.

The team already has been contacted by a few semiconductor manufacturers about the technology.

"Were not that far off. It's almost ready," said Arbabian. "We might need six months to refine some components. We need more time for some added features, like extra sensors. We have the foundation so it's not a difficult addition."

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